Combustion chamber fairing



muy A June 21, 1955 Filed June 14, 1951 J. M. WETZLER 2,711,072

COMBUSTION CHAMBER FAIRING 2 Sheets-Sheet l June 21, 1955 M, WETZLER2,7ll,072

COMBUSTION CHAMBER FAIRING Filed June 14, 1951 2 Sheets-Sheet 2Ltjornegs Unite tates Patent aan COMBUSTION CHER FAIRING .lohn M.Wetzler, Indianapolis, Ind., assigner to General Motors Corporation,Detroit, Mich., a corporation of Delaware Application .lune 14, 1951,Serial No. 231,436

7 Claims. (Cl. (itl-39.37)

This invention relates to combustion chambers of a type suited for usein gas turbine engines or the like, and, more particularly, tocannular-type combustion chambers.

The cannular-type combustion chamber, in contradistinction to thearrangement of a plurality of individual combustion chambers commonlyused heretofore in gas turbine engines, is a single annular chamber ofrelatively large diameter in relation to that of said individualcombustion chambers and is constituted by concentric cylindrical outerand inner casings between which a plurality of inner combustion linersare mounted. Though possessing certain structural and operatingadvantages, the cannular combustion chamber presents a dimcult problemwith regard to the maintenance of a straight line air flow past theinner liners thereof. The compressor discharge air in passing throughthe combustion chamber inlet casing into the combustion chamber tends toswirl and creates an undesirable cross-flow condition across the innerliners so as to interfere with the combustion process and reduce theoperating efficiency of the engine. This condition is not encountered oris, at least, substantially mitigated in gas turbine engines employing aplurality of individual combustion chambers.

The present invention aims generally toward improving the air flow incannular-type combustion chambers, and has as its principal objectivethe provision of a cannular combustion chamber which simulates theaction of individual combustion chambers and substantially prevents theestablishment of a cross-ow condition therein.

A further object is to provide suitable means adapted to be compactlyembodied in a cannular combustion chamber for the accomplishment ofthese general ends without additional space requirements or modicationof the engine.

The preferred manner in which these and other objects are accomplishedand the advantages of the invention will be apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

Fig. 1 is a fragmentary sectional elevation of a combuston chamber inletcasing and the inlet end of a cannular combustion chamber embodying apreferred form of the invention, the section being taken in the plane 11 of Fig. 2;

Fig. 2 is a partial transverse section of Fig. 1 taken in the plane 2 2thereof;

Fig. 3 is a fragmentary section of Fig. 2 taken in the direction 3 3thereof; and

Fig. 4 is a perspective View of one of the elements of the presentinvention.

Referring to thedrawings, Fig. 1 is a fragmentary sectional elevation ofa combustion chamber inlet casing j and the inlet end of a cannularcombustion chamber 12 embodying a preferred form of the invention.

The inlet casing 10 forms the mid-frame, which is one of the mainstructural support members of a gas turbine m ICE Z end of the mid-frameis adapted to be connected to the discharge end of a rotary compressor(not shown) which may be of the multi-stage axial llow fluid dynamictype.

The mid-frame 10 may be a fabricated sheet steel structure formed by acylindrical outer casing 14 and a frusto-conical inner casing section 15the forward and aft ends of which are supported by axially-aligneddisklike face plates 16 and 17. The inner casing section 15 is supportedfrom the outer casing 14 by a plurality of equally spaced hollow radialsupport struts 20 which extend substantially throughout the length ofthe rearwardly-diverging annular compressor outlet diffusing passage 24defined by the outer casing 14 and inner casing section 15. The supportstruts have a double-convex or lenticular cross section as shown in thesectional view of Fig. 3, some of the struts being radially aligned withmounting pads 25 disposed about the periphery of the outer casing 14.

Extending circumferentially about the interior of the forward end of themid-frame 10 is the compressor outlet 26 formed by an annulus containingtwo stationary annular rows of discharge guide vanes or straighteningvanes 2S, 29 mounted in concentric outer and inner shroud rings 31 and32, respectively, the annulus being supported principally by the innershroud ring 32 suitably secured to the forward face plate 16 and theinner casing section 15 as shown in Fig. l. Flanges 36, 37 are providedat the forward and aft ends, respectively, of the outer casing 14 of themid-frame 10 to permit fastening thereof by bolts (not shown) to matingflanges on the compressor casing and combustion chamber assembly,respectively.

The cannular combustion chamber 12 comprises a split outer casing formedby a pair of semi-cylindrical segments which are bolted together and areconcentrically disposed about a cylindrical inner casing 42. The outerand inner casings 40, 42 of the combustion chamber deline a largeannular passage which contains a plurality of combustion chamber innerliners 44 disposed in a circular array and mounted in spaced relationtherein, the inner liners being centrally aligned between and locatedbehind adjacent support struts 20 of the mid-frame 10 as shown in Fig.2. Bolting flanges 46, 47 extending about the forward ends of the outerand inner combustion chamber casings 40, 42, respectively, are providedto fasten the combustion chamber to the rear flange 37 and face plate 17at the discharge end of the mid-frame, which supports the combustionchamber. The forward portion of the outer and inner combustion casingsare faired outwardly and inwardly, respectively, to provide a smoothcontinuous transition between the diverging discharge end of themid-frame 1t) and the inlet end of the combustion chamber as shown. y

The combustion chamber inner liners 44 each comprises a dome-shapedforward member 50 which forms a detach- I able cap for a cylindricalburner shell 52, the latter member extending axially of the combustionchamber and having perforations (not shown) about its periphery forpurpose of admitting compressed air to support the combustion processtaking place therein. The dome 50 of the inner liner has a flangedannular central opening 54 therein to receive the spray tip 56 of an L.shaped fuel nozzle 57 which extends forwardly into the mid-frame l()between adjacent support struts 20 thereof and emerges through anopening 53 in the outer casing 14 over which is bolted an externalnozzle mounting flange 59 near the aft end of the mid-frame. The burnershells 52 of the inner liners 44 are supported in spaced relationbetween the outer 40 and the inner 42 combustion chamber casings bysaddle support members @welded to the inner casing as shown in thetransverse view of Fig. 2.

In accordance with the invention, the compressor discharge air isprevented from setting up a cross-ilow'condition across the domes of thecombustion chamber inner liners by means of a combustion chamber fairingwhich is positioned in the .combustion chamber to simulatev the actionof theairiiow in individual combustion chambers. The Ycombustion chamberfairing comprises aplurality of radialbames orow splitter plates S eachdisposed in the inlet end of the .combustion chamber i2 between adjacentinner liners so as toenclose the forward portion of each inner liner ina segmented annular compartment formed by a pair of adjacent splitterplates and a curved portion of the outer and-inner combustion chambercasings 4d and 42 as shown in Fig. 2.

One of the splitter plates is shown in perspective elevation in Fig. 4as a thin plate having a recess or em bossment 66 therein to increaseits rigidity,A the shape of the plate conforminggenerallyy with thecontours of the inlet portion of the `combustion chamber. A mounting tab68 formed at the trailing end of the outer extremity 70 of the splitterplate of Fig. 4 permits fastening thereof to the outer combustionchamber casing 4i? by means of a partially threaded bolt 73, the upperportion. `of which is threaded through a nut welded to-the voutercasing, the lower portion of the bolt 73 forming an unthreaded pin 76 ofreduced diameter and extending internally-of the combustion chamber toengage analigned opening in a washer 77 welded to the mounting tab Vasshown in Figs. 1 and 2. A similar mounting tab 78 formed at` the innerextremity 80 of the splitter plate of. lidg.,4 and located between theforward and trailing edges. till, 52, respectively, thereof is adaptedto be lsecured to the inner combustion casing 42 by a threaded bolt 83associated with an aligned nut and washer 8S land 86 welded to the innersurface of the combustion chamber inner casing as shown in Fig. l.

The forward edge 8l of the splitter plate 65 is detachably mounted in abracket connection 89 which is formed by a pair of juxtaposed springmetallic strips 9d, 9i and has bifurcations at each end thereof as shownin Fig. 3, the strips being seam-welded together betweenthe bifurcatedends of the bracket. bracket S9 is welded to the trailing edge of theinlet casing support strut 20 behind which the splitter plate isaligned. The bifurcated trailing end of the bracket constitutes a"knife-blade connection which resiliently engages the forward edge ofthe splitter plate and forms a v rigid support therefor. The innermosttrailing edge of the splitter plate is detachably mounted in anotherknifeblade bracket connection 93 formed by a pair of spring metallicoutwardly extending L-shaped strips 94, 9S welded to lthecornbustionchamber inner casing d?. as

shown in Figs. l, 2 and 3.

The splitter plates 65 and connecting brackets 59 conystitute anextension of the inlet casing support struts 2.@

into the combustion chamber so as to form an etective partition whichsubstantially prevents the establishment of a cross-flow condition ofthe compressor discharge air across the inner combustion liners andmaintains a straight line ow thereby. In the preferred embodiment of theinvention, the splitter plates extend axiallyfrom the inlet of thecombustion chamber slightly beyond the dome-shaped forward portion ofthe inner combustion liners, although the plates could extendsubstantially throughout the entire length of the combustion chamber ifdesired.

Although a specific embodiment of the invention has been shown anddescribed, it will be understood that it is but illustrative and thatvarious modiiications may be made therein without departing from thescope and spirit of this invention.

What is claimed-is:

1. In combination, a rotary compressor, a single annular combustionchamber, a combustion Achamber inlet casing between said compressor andcombustion chamber, said inlet casing comprising a rearwardly extendingannular diffusing passage having a plurality of radial- The forward edgeof the ly disposed support struts therein, said combustion chambercomprising a cylindrical outer easing and a cylindrical inner casingconcentric with said cuter casing, and akk plurality of cylindricalinner combustion liners mounted in spaced relation between said outerand inner combustion chamber casings, and apiurality of radially dis-Vposed flow-splitter plates detachably mounted to respec casing betweensaid compressor and combustion chamher, said inlet casing comprising arearwardly extending annular ditusing passage having a plurality ofradially radially disposed support struts therein, said combustionchamber comprising a cylindrical outer casing and a cylindrical innercasing concentric with said outer casing, and a plurality of cylindricalinner combustion liners mounted in spaced relation between said outerand inner combustion chamber casings, and a plurality of radiallydisposed dow-splitter plates extending axially of said combustionchamber between adjacent ones of saidinner combustion liners, theforward edge of each of said flow-splitter plates being detachablymounted in knife-blade bracket connections secured to respective ones ofsaid inlet casing support struts.

3. In a combustion apparatus comprising, in combination, an outer casingand an inner casing coaxial with said outer casing and deiiningtherewith an axiallyextending annular passage having an inlet portionand an outlet portion at the respective ends thereof, a plurality ofspaced burners extending axially of said passageand mounted thereinbetween said outer and inner casings and a plurality of radiallydisposed iiow divider lplates positioned in the inlet of said passagebetween adjacent ones of said burners and extending axially of saidpassage,V

said iiow divider plates dividingthe inlet portion of said combustionapparatus into a plurality of compartments each containing one of saidburners and simulating a plurality of separate combustion chambers insaid cornbustion apparatus.

4. In a combustion apparatus comprising, in combination, an outer casingand an inner casing coaxial with said outer casing and deiinng therewithan axially extending annular passage havingk an inlet portion and anoutlet portion at the respective ends thereof, a plurality of spacedburners extending axially of said passage and mounted therein betweensaid outer and inner casings, and a plurality of detachably mounted flowdivider plates radially disposed in the inlet of said passage betweenadjacent ones of said burners and extending axially of said passage,said ow divider plates dividing the inlet portion or" said combustionapparatus into a plurality of compartments each containing one of saidburners andsimulating a plurality of separate combustion chambers insaid combustion apparatus.

5. A gas turbine engine comprising, in combination, a turbine-drivencompressor, a single annular combustion apparatus and an annular inletcasing betweensaid compressor andk said combustion apparatus havingpassage means dened therein for supplying the combustion apparatus fromthe compressor, said combustion apparatus including an outer wall, aninner wall coaxial `with the f outer wall and deiining therewith a largeannular coming axiallyfrom a point slightly forward ofsaid burners.

a part of the length thereof, said iow dividerrfvrneans dividing theinterior of said combustion chamber into a plurality of compartmentseach containing one of said burners and simulating a plurality ofseparate smaller combustion chambers in said large combustion chamber.

6. In a gas turbine engine including a turbine-driven compressor, acombustion apparatus and an inlet casing, said inlet casing defining anaxially extending annular passage between said compressor and saidcombustion apparatus and having a plurality of radially disposed supportstruts therein, said combustion apparatus comprising, in combination, anouter casing wall, an inner casing wall coaxial with the outer casingWall and defining therewith a large annular combustion chamber extendingaxially of the engine and having an inlet portion and an outlet portion,a plurality of spaced burners extending axially of said chamber andmounted between said outer and inner casing walls, a plurality ofradially disposed ow divider plates in the inlet of said cornbustionchamber and positioned between adjacent ones of said burners, said iowdivider plates being proximate to and aligned with respective ones ofsaid inlet casing support struts and dividing the inlet of saidcombustion apparatus into a plurality of compartments each containingone of said burners, said compartments simulating a plurality ofseparate smaller combustion chambers in said large combustion chamber.

7. In a gas turbine engine including a turbine-driven compressor, asingle annular combustion apparatus and an annular inlet casing betweensaid compressor and said combustion apparatus, said annular inlet casingdening an axially extending annular passage between said compressor andsaid combustion apparatus and having a plurality of radially disposedsupport struts therein, said combustion apparatus comprising incombination, an outer casing wall and an inner casing wall coaxial withthe outer casing wall and defining therewith a large annular combustionchamber extending axially of the engine and having an inlet portionadapted to be connected to said annular inlet casing and an outletportion, a plurality of spaced burners extending axially of saidcombustion chamber and mounted between said outer and inner casing wallsthereof, and a plurality of radially disposed How-splitter plates in theinlet of said combustion chamber and positioned between adjacent ones ofsaid burners, each of said flow-splitter plates being adapted to beconnected at its forward end to a respective one of said inlet casingsupport struts and extending axially of said combustion chamber a partof the length of the burners therein.

References Cited in the tile of this patent UNITED STATES PATENTS2,479,573 Howard Aug. 23, 1949 2,545,495 Sforzin Mar. 2l, 1951 2,548,886Howard Apr. 17, 1951 2,595,999 Way et al May 6, 1952 FOREIGN PATENTS936,276 France Feb. 16, 1948

